Among viruses, human immunodeficiency virus (HIV), a kind of retrovirus, is known to cause acquired immunodeficiency syndrome (AIDS). The therapeutic agent for AIDS is mainly selected from a group of reverse transcriptase inhibitors (e.g., AZT, 3TC) and protease inhibitors (e.g., Indinavir), but they are proved to be accompanied by side effects such as nephropathy and the emergence of resistant viruses. Thus, the development of anti-HIV agents having the other mechanism of action has been desired.
On the other hand, a multidrug combination therapy is reported to be efficient in treatment for acquired immunodeficiency syndrome (AIDS) because of the frequent emergency of the resistant mutant. Reverse transcriptase inhibitors and protease inhibitors are clinically used as an anti-HIV agent, however, agents having the same mechanism of action often exhibit cross-resistance or only the additional activity. Therefore, anti-HIV agents having the other mechanism of action are desired.
Under such the circumstance, as an anti-HIV drug of a novel mechanism, an integrase inhibitor is paid an attention (see: Patent Documents 1,2). In addition, as an anti-HIV drug having the same action, carbamoyl-substituted hydroxypyrimidinone derivatives (see: Patent Documents 3,4) and carbamoyl-substituted hydroxypyrrolidione derivatives (see: Patent Document 5) are known. In addition, there has been an application directed to carbamoyl-derivative hydroxypyridone derivatives (see: Patent Document 6, Example 8).
As other carbamoylpyridone derivatives, 5-alkoxypyridine-3-carboxamide derivatives and γ-pyrone-3-carboxamide derivatives are known, and they are a plant growth suppressing agent and a herbicide (see : Patent Document 7 to 9).    [Patent Document 1]    WO 03/0166275    [Patent Document 2]    WO 2004/024693    [Patent Document 3]    WO 03/035076    [Patent Document 4]    WO 03/035076    [Patent Document 5]    WO 2004/004657    [Patent Document 6]    Japanese Patent Application No.2003-32772    [Patent Document 7]    Japanese Patent Application Laid-Open (JP-A) No.2-108668    [Patent Document 8]    JP-A No.2-108683    [Patent Document 9]    JP-A No.2-96506
Under the above circumstance, the development of a novel integrase inhibitor has been desired.